ERBB2 and breast carcinoma: While women with HR+/HER2+ breast cancer were underrepresented (n = 695, 12%), a subgroup analysis in this cohort demonstrated an improved DFS with the addition of OS to an AI (8 year DFS 75.2% exemestane plus OS vs. 68.3% tamoxifen, HR 0.75, 95% CI 0.45–1.22) or tamoxifen (8 year DFS 85.4% tamoxifen plus OS vs. 68.3% tamoxifen, HR 0.41, 95% CI 0.22–0.75).4